x86-64: Use PLT address for PC-relative reloc

Since PLT in PDE and PC-relative PLT in PIE can be used as function
address, there is no need for dynamic PC-relative relocation against
a dynamic function definition in PIE.  Linker should resolve PC-relative
reference to its PLT address.

NB: i386 has non-PIC PLT and PIC PLT.  Only non-PIC PLT in PDE can
be used as function address.  PIC PLT in PIE can't be used as
function address.

bfd/

	PR ld/22842
	* elf32-i386.c (elf_i386_check_relocs): Pass FALSE for non
	PC-relative PLT to NEED_DYNAMIC_RELOCATION_P.
	* elf64-x86-64.c (elf_x86_64_check_relocs): Create PLT for
	R_X86_64_PC32 reloc against dynamic function in data section.
	Pass TRUE for PC-relative PLT to NEED_DYNAMIC_RELOCATION_P.
	(elf_x86_64_relocate_section): Use PLT for R_X86_64_PC32 reloc
	against dynamic function in data section.
	* elfxx-x86.c (elf_x86_allocate_dynrelocs): Use PLT in PIE as
	function address only if pcrel_plt is true.
	(_bfd_x86_elf_link_hash_table_create): Set pcrel_plt.
	* elfxx-x86.h (NEED_DYNAMIC_RELOCATION_P): Add PCREL_PLT for
	PC-relative PLT.  If PLT is PC-relative, don't generate dynamic
	PC-relative relocation against a function definition in data
	secton in PIE.  Remove the obsolete comments.
	(elf_x86_link_hash_table): Add pcrel_plt.

ld/

	PR ld/22842
	* testsuite/ld-i386/i386.exp: Run PR ld/22842 tests.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-i386/pr22842a.c: New file.
	* testsuite/ld-i386/pr22842b.S: Likewise.
	* testsuite/ld-x86-64/pr22842a.c: Likewise.
	* testsuite/ld-x86-64/pr22842a.rd: Likewise.
	* testsuite/ld-x86-64/pr22842b.S: Likewise.
	* testsuite/ld-x86-64/pr22842b.rd: Likewise.

1 files changed, 31 insertions, 19 deletions

diff --git a/bfd/elfxx-x86.h b/bfd/elfxx-x86.h
index 0162a90c6d3..f84fe01630b 100644
--- a/bfd/elfxx-x86.h
+++ b/bfd/elfxx-x86.h
@@ -76,14 +76,11 @@
    into the shared library.  However, if we are linking with -Bsymbolic,
    we do not need to copy a reloc against a global symbol which is
    defined in an object we are including in the link (i.e., DEF_REGULAR
-   is set).  At this point we have not seen all the input files, so it
-   is possible that DEF_REGULAR is not set now but will be set later (it
-   is never cleared).  In case of a weak definition, DEF_REGULAR may be
-   cleared later by a strong definition in a shared library.  We account
-   for that possibility below by storing information in the relocs_copied
-   field of the hash table entry.  A similar situation occurs when
-   creating shared libraries and symbol visibility changes render the
-   symbol local.
+   is set).
+
+   If PCREL_PLT is true, don't generate dynamic relocation in PIE for
+   PC-relative relocation against a dynamic function definition in data
+   section when PLT address can be used.
 
    If on the other hand, we are creating an executable, we may need to
    keep relocations for symbols satisfied by a dynamic library if we
@@ -91,23 +88,30 @@
 
    We also need to generate dynamic pointer relocation against
    STT_GNU_IFUNC symbol in the non-code section.  */
-#define NEED_DYNAMIC_RELOCATION_P(INFO, H, SEC, R_TYPE, POINTER_TYPE) \
+#define NEED_DYNAMIC_RELOCATION_P(INFO, PCREL_PLT, H, SEC, R_TYPE, \
+				  POINTER_TYPE) \
   ((bfd_link_pic (INFO) \
     && (! X86_PCREL_TYPE_P (R_TYPE) \
 	|| ((H) != NULL \
 	    && (! (bfd_link_pie (INFO) \
 		   || SYMBOLIC_BIND ((INFO), (H))) \
 		|| (H)->root.type == bfd_link_hash_defweak \
-		|| !(H)->def_regular)))) \
-		|| ((H) != NULL \
-		    && (H)->type == STT_GNU_IFUNC \
-		    && (R_TYPE) == POINTER_TYPE \
-		    && ((SEC)->flags & SEC_CODE) == 0) \
-		    || (ELIMINATE_COPY_RELOCS \
-			&& !bfd_link_pic (INFO) \
-			&& (H) != NULL \
-			&& ((H)->root.type == bfd_link_hash_defweak \
-			    || !(H)->def_regular)))
+		|| (!(bfd_link_pie (INFO) \
+		      && (PCREL_PLT) \
+		      && (H)->plt.refcount > 0 \
+		      && ((SEC)->flags & SEC_CODE) == 0 \
+		      && (H)->type == STT_FUNC \
+		      && (H)->def_dynamic) \
+		    && !(H)->def_regular))))) \
+   || ((H) != NULL \
+       && (H)->type == STT_GNU_IFUNC \
+       && (R_TYPE) == POINTER_TYPE \
+       && ((SEC)->flags & SEC_CODE) == 0) \
+   || (ELIMINATE_COPY_RELOCS \
+       && !bfd_link_pic (INFO) \
+       && (H) != NULL \
+       && ((H)->root.type == bfd_link_hash_defweak \
+	   || !(H)->def_regular)))
 
 /* TRUE if dynamic relocation should be generated.  Don't copy a
    pc-relative relocation into the output file if the symbol needs
@@ -482,6 +486,14 @@ struct elf_x86_link_hash_table
   /* TRUE if GOT is referenced.  */
   unsigned int got_referenced : 1;
 
+  /* TRUE if PLT is PC-relative.  PLT in PDE and PC-relative PLT in PIE
+     can be used as function address.
+
+     NB: i386 has non-PIC PLT and PIC PLT.  Only non-PIC PLT in PDE can
+     be used as function address.  PIC PLT in PIE can't be used as
+     function address.  */
+  unsigned int pcrel_plt : 1;
+
   bfd_vma (*r_info) (bfd_vma, bfd_vma);
   bfd_vma (*r_sym) (bfd_vma);
   bfd_boolean (*is_reloc_section) (const char *);